Speed-sensitive governing means



NOV. 26, 1940. G, J, TRAPP 2,222,919

'SPEED-SENSITIVE GOVERNING MEANS Filed Aug. 13, 1956 www@ Jgd f PatentedNov. 26, 1940 UNITED- sTATEs SPEED-.SENSITIVE GOVERNING MEANS GeorgeJoseph 4jlrapp, London, England, assignor to Automotive Products CompanyLimited, London, England Application August 13, 1936, 'Serial No. 95,947

In Great Britain August 13, 1935 claims. (ci. fzs-14o) 'Thisinvention'relates to governing means operating by fluid pressure, andparticularly to speed-sensitive governing means for injection pumps, andit has for its object to provide an 5 improved method of operation which.not only simplifies the general construction of governing meansoperated by uid pressure, but also provides advantages in practice, theforemost of which is the ready capability of altering the char- 1`0acteristics of the governor to suit the injection pump or othermechanism which is being governed.

The invention broadly consists in the incorporation in a fluid-pressureoperated governor,

of a movable plunger or equivalent which is acted upon by the pressurein question and which serves to controlor modify the passage of saidiiuidthrough a constriction. Thus alterations in the pressure intensityof the fluid mayautomatically adjust the resistance-afforded by the Yconstriction according to the actual position of the plunger orequivalent, this alteration being Y under the control of the designer toa very large extent, owing to the great number of modifications whichcan be made in theformation of the orice and the manner in which thecharacteristics thereof change in sympathy with alterations in thepressure .of the fluid. For this purpose the constriction is preferablyprovided between the plunger and a suitable housing accommodating saidplunger,` the shape and proportions of the plunger being arranged inconjunction lwith the shape and proportions of the housing,

and the normal position of the plunger in respect to the housing beingso designed, that changes in the fluid pressure bring about the desiredmovements ofthe plunger for actuating the usual controlling means, suchfor example as the rack bar or bars of a fuel injection pump. l l 4o Theinvention accordingly provides a govrnor device actuated by fluidpressure and comprising a passageway through whichV iiuid is caused topass, and a movable plunger member disposed therein so as to produce aconstriction, thus 5 creating a pressure difference on the two ends ofthe plunger and causing the latter to move along the passageway to anextent determined by the pressure of the fluid in advance of theplunger.

As a further feature the invention provides an improved arrangement andconstruction of fuel injection pump unit having a rotary feed pumpdriven by the usual cam shaft of the injection pump, a hydraulicgovernor fed from the delivery 55 of the feed pump and mechanismconnecting said hydraulic governor with the usual controlling means,such as the rack bars of the fuel injection pump. Preferably thegovernor device comprises a plunger member which partially closes apassage fed with liquid from a pump driven 5 with the injection pump,movement of said plunger being arranged to control the delivery of theinjection pump, and a relief valve, adapted to limit the pressure of theliquid acting on the back of the plunger member. This relief .valve 10may serve also to increase the pressure of the liquid fed to theinjection cylinders or equivalent as the speed of the pump increases.

Examples of the invention are shown in the accompanying diagrammaticdrawing in which l5 Figure 1 is a side elevation partly in sectionshowing a fuel injection pump fitted with the improved governorarrangement and pressure l relief valve;

Figures 2, 3, 4 and 5 show modified shapes of 20 passageway and plungermember;

Figure 6 is a fragmentary sectional elevation showing a furthermodification in the -design of the passageway and plunger member; and

Figure 7 shows in side elevation an alternative 25 form of packing fortheplunger member.

In the arrangement shown in Figure 1 a twocylinder injection pump isindicated at I Il, and is provided upon the undriven end of its camshaft Il with a feed pump I2 which is supplied 3o Y from a suitablereservoir (not shown) by means of a pipe I3, a filter I4 being includedin the pipe I3, if desired. The delivery from the feed pump I2 is takenthrough a pipe I5 to a governor housing I6 secured at one end of theusual inlet 35 duct I1 of the pump, the inlet branches leading to therespective cylinders being indicated at I8 and I9 respectively. v

At the other end of the inlet duct I'I a relief or pressure-controllingmushroom valve 20 is fit- 40 ted in a guide 2|, and is normally held onits seating by a coiled compression spring 22 bearing upon an adjustingscrew. The valve 2B serves to maintain a substantially constant pressurewithin the duct I1, as the feed pump I2 is pref- 45 erably arranged tohave at any particular speed an output which is many times in excess ofthe quantity of fuel that could possibly be taken by the cylinders ofthe injection pump Il) with a view to providing powerful and eilicientgoverning; The excess fuel, therefore, passes through a pipe 24 and isreturned to the feed pump inlet passage, which is indicated at 25. Thevalve 20 may if desired be formed with a comparatively restrictedpassageway along its At vits interior the governor housing I6 is formedwith a cylindrical surface 26 Within which a plunger member 21isdisposed, said plunger member being supported by means of a stem 28which is slidably mounted in a well-fitting bush 29. Towards its outerend the stem 28 is-tted with an abutment washer 30 against which bears acomparatively light coiled compression spring 3|, the other end of thelatter being carried by a cup-shaped intermediate member 32, the rim ofwhich in turn engages with a stronger coiled compression spring 33bearing at its other end upon the governor housing I6. Thus the plungermember 21 is normally drawn towards the left, although the positionshown in Figure 1 is that which would normally be occupied while thepump is running at a speed corresponding to the idling speed of theengine. It will be seen that the plunger member 21 has its back part 34substantially cylindrical in form, a slight clearance only beingprovided between this part and the interior surface 26 of the governorhousing. At its front part, however, indicated at 35, the plunger memberistapered so that as said member moves to the right the length of theconstriction formed by the slight clearance between the part 34 and thebore 26 progressively diminishes, after which the tapered part 35 comesopposite the mouth 36 of the governor housing I6, thus causing theconstriction to get larger in cross-sectional area as the plunger member21 moves further to the iight. It will be appreciated that this movementis occasioned by the pressure developed as a result of fuel being forcedthrough the restriction by the pump I2 and the actual movement will be ameasure of this pressure. `Moreover, as this pressure is again dependentupon the speed at which the pump is driven it will be evident that theposition occupied by the plunger member 21 will be that in which thepressure difference between the interior 31 of the governor housing I6and the inlet conduit I1 produces a. force upon the plunger member 21equal to that developed by the two compression springs 3| and 33,neglecting of course all frictional and other losses. It will be seen,therefore, that the plunger member 21 produces an eiect similarto thatof a centrifugal governor, and it can be used for controlling thedelivery of the injection pump for the purpose of providing steadyrunning of an engine. In the example shown the stem 28 is iitted at itsouter end with a transverse pin 38 which is engaged by the upper notchedend of a lever 39, which is located by means of a slot 4I) which slidesupon a spindle 4I, the lower end of the said lever 39 being inengagement with a pin 42 serving as the fulcrum of the lever. A furtherslot 43 engages a pin 44 carried upon the usual quantity control rod 45of the injection pump, so that when the speed of the latter increasesthe upper part of the lever 39 is moved to the right about the pin 42,thus also moving the control rod 45 to the right and reducing thequantity of fuel injected. With a view to adjusting the speed of theengine the pivot pin 42 is itself mounted for angular movement about thespindle 4I, as indicated by the arrows.

The nature and the extent of movement of the plunger member 21 will, ofcourse, to a large degree depend upon the shape of this member inrelation to the interior surface of the governor housing I6, and variousmodifications are, therefore, shown in Figures 2 to 5 of the drawing. InFigure 2 the interior surface 26 of the governor housing I6 is againcylindrical but the plunger member 21 is formed at its front with acylindrical portion 4,6, thus in effect slightly increasing thesensitivity of the governor at full load when the part 46 will, ofcourse, be approximately opposite the mouth 36 of the housing I6.

yIn Figure 3 the plunger member 21 is tapered throughout its'entirelength, and is arranged to engage with a correspondingly tapered surface41 within the interior of the governor housing I6. In this example theclearance 48 between the overlapping parts of the governor housing I6and the plunger member 21, progressively increases as the latter movesaway from its inoperative position. A somewhat similar construction isshown in Figure 4, where the taper of the plunger 24 and the housingsurface 41 is reversed with a view to providing increased sensitivity asthe pressure increases, thus compensating for any falling off in therate of increase of the feed pump delivery `as the speed increases.

A further modication is shown in Figure 5 where the major part of theplunger member 21 is cylindrical in form, but said member is providedupon its back portion with a flange 49 affording the desired smallclearance, which is indicated at 50. As the speed of the injection pumpincreases the plunger member 21 is progressively moved against theaction of its return spring until such time as the flange 45 projectsbeyond the mouth 36 of the governor housing, as indicated in brokenlines, thus considerably reducing the sensitivity of the governor beyondthis point.

Figure 6 shows a further constructional form of governor assembly, andin this case the plunger annular anges, indicated at 5U and 5Irespectively, the desired small clearance being between the outerextremities of these anges and the interor surface of thegovernorhousing I6. The stem 28 is formed with a pair of shallow grooves 52serving to prevent leakage, while a fluid connection between the pipe I5and the housing I6 is effected by means of a banjo connection 53 whichis tightened axially on to the governor housing I6 by means of a nut 54.It will be seen in Figure 6 that the plunger member 21 is formed at itsfront end with a frusto-conical valve seating 56, which, when thegovernor is in its off position completely closes the inlet passage 51.Thus, should the plunger member 21 tend to stick after a period ofdisuse, the pressure generated by the feed pump will be ample todislodge said member.

'I'he shape of the plunger member 21 and of the housing surface 26 mayof course be varied in order to provide any particular form ofcharacteristic for the governor, so that the injection pump unit as awhole may conform to the characteristics of the engine for which it isintended. Particularly is this the case where the improvedfluid-actuated governor is used in conjunction with a governor accordingto our co-pending application No. 36,413, filed Aug. l5, 1935, issuedMay 24, 1938 as Patent No. 2,118,578 arranged to modify the timing ofthe injection in sympathy with the speed and load of the engine, inaddisistant rubber or other appropriate material and having a relativelysmall diameter in order that the preponderance of pressure may act uponthe member 21, is used for providing a liquid-tight joint which permitsfree sliding movement of the stem 28. It will, of course, be obviousthat any other sliding packing such as those fof 'the cup leather typeor the gland type may be used.

-The means used for controlling the governor, for example the twosprings 3i and 33 shown in Figure 1, may be modified as desired, inaccordance with the Work vto be carried out by the governor.

In Figure 1 the spring 3i is a light one to control the engine speedwhen idling, whilst the spring 33 is of much greater strength, and doesnot yield until the engine reaches the maximum speed at which' it isdesigned to run, so that the governor controls the idling speed and themaximum speed of the engine but is ineffective within the useful Workingspeed range of the engine. This form of governing is a normalrequirement for transport engines.

As soon as the engine speed rises above'the idling speed the spring 3lyields, and the plunger member 21 moves inwardly until the abutmentwasher 30 contacts with the cup-shaped member 32, further movement beingthen prevented by the stronger spring 33 until the engine reaches itsmaximum speed.

For constant speed governing, such as is required for a marine engine, asingle spring or its equivalent, which might be initially loaded, couldbe used as is common in governor practice.

Further, the present invention is not necessarily hunted to fuelinjection pumps as it may be satisfactorily employed wherever there isasource of liquid, the pressure of which varies' according to the speedof the mechanism to be controlled.

What I claim is:

1. A fuel injection pump unit including, in

combination with a fuel injection pump having.

an inlet passage, a feed pump driven in cdmmon with the fuel injection-pump and a source of fuel, a governor including a housing having a boreprovided with a cylindrical surface, said .bore communicating with theinlet passage, means connecting the bore with the feed pump,

a governor plunger axially shiftable within the bore. said plungerhaving a stem extending exteriorly ofthe housing and having asubstantially cylindrical back portion and a tapered portion, said backand tapered portions being spaced from the cylindrical surface. andspring means on the plunger stem for normally urging said plunger stemin the boreaway fromv the inlet passage, said tapered portion and saidVback portion defining a constriction and receiving thereagainst fuelunder pressure from the first mentioned means, said fuel under pressureshifting the plunger toward the inlet passage and against the tension ofthe means on the stem for maintaininga position of equilibrium for theplunger with respect to pressure dierences between the two sides of theplunger.

2. In a fuel injection pump unit, in combination with a fuel injectionpump having an inlet passage, a feed pump driven in common with the fuelinjection pump and a source of fuel, a governor including a housinghaving a bore provided with a cylindrical surface, said borecornmunicating with the inlet passage, means for leading fuel from thefeed pump to the housing, a governor plunger in the bore and having aback portion and a tapered portion dening a constriction in the housing,and means normally urging the plunger away from the inlet passage, fuelunder pressure in the housing impinging on the tapered portion of theplunger and passing the constriction into said inlet passage causingshifting said plunger toward the inlet passage whereby a position ofequilibrium for the plunger with respect to pressures at opposite sidesof said plunger will be maintained.

3. In a fuel injection pump unit asrecited in claim 2, a relief valve inthe inlet passage, and a v return pipe leading from the relief valve tothe feed pump, said' relief valve maintaining fuel pressure in the inletpassage substantially constant.

4. In a. fuel injection pump unit, in combination with a fuel injectionpump having an inlet passage, a feed pump driven in common with the fuelinjection pump and a source of fuel, a governor including a. housinghaving a bore provided with acylindrical surface, said borecommunicating with the inlet passage. means for leading fuel from thefeed pump to the housing, a governor plunger in the bore and having aback portion Iand a tapered portion defining a constriction in thehousing, means normally urging the plunger away from the inlet passage,fuel under pressure in the housing impinging on the tapered portion ofthe plunger and passing the constriction into said inlet passage causingshifting said plunger toward the inlet passage whereby a position ofequilibrium for the plunger with respect to pressures at opposite sidesof said plunger will be maintained. and means connected :with theplunger and operable by movement quantity control rod being carried bythe fuel,

injection pump, a spindle, and a lever operatively connected with thefulcrum, the quantity control rod, the spindle, and the free end of theplunger stem.

GEORGE JOSEPH TRAPP.

